Two problems are generally encountered during the processing of harvested fruits and vegetables: managing year-round availability of fresh fruit and vegetables when the harvests are brief and seasonal; and storing the harvested products for long periods of time in warehouses, distribution centers and retail outlets without sacrificing freshness, quality and consumer appeal. The invention and its embodiments described herein improve apparatuses, methods and systems used to currently address these problems.
Fruits and vegetables start deteriorating in quality at some rate immediately following the harvest, caused by physical, chemical, enzymatic or microbiological reasons. To complicate the problem, the majority of fruit and vegetables are only seasonally available. In some cases, e.g., apricots, the season is shorter than a month. While it may be theoretically possible to harvest produce regularly at any time in at least one part of the world by taking advantage of the difference in climates and growing seasons, it is rarely economically viable to transport them from different parts of the world to the place where they are needed fresh year round. Locally grown fruits and vegetables are often also preferred over imports. For these reasons, the food industry has generally adopted the practice of preserving fruits and vegetables temporarily in bulk after harvest for later year-round supply to consumers.
Current methods for commercially processing harvested fruits and vegetables involve cleaning, preparation and blanching, canning the fruit with a packing medium, and conventional sterilization and stabilization methods using established retort processing (See FIG. 1). The retort process uses heat treatment, which can be particularly harsh for some fruits and vegetables, and causes undesirable physical and chemical changes which decrease product quality. These changes affect color, texture and appearance, alter flavor or destroy the existing endogenous nutrients in the fruits and vegetables. Color degradation also occurs because of Maillard browning reactions between sugar (e.g., fruit sugars such as glucose or fructose) and protein. Maillard browning is heat induced and, initially, produces colorless browning precursors. These precursors eventually become brown pigments as heat-treated fruit and vegetables age. The generation of precursors is directly related to the intensity of the heat treatment of the fruit and vegetables, and the conventional retort process, which typically focuses primarily on sterilization and product safety, can use excessive heat, which in turn results in the formation of more browning pre-cursors and directly results in reduced shelf life. Further, excessive heat can also caramelize the sugars in fruits and vegetables, further degrading product quality and shelf-life.
The packing medium used for storing retort-processed fruits and vegetables is generally a liquid that is either syrup (sugar, water with other ingredients) or brine (salt water with other ingredients). Typically the ratio of fruit to packing medium is about 60:40, and there is a desire to decrease the amount of packing medium required, so that there is more efficient use of the packaging and storage space. There is also interest in increasing the size of the product containers processed by retort. Since the retort-based stabilization process relies on conductive and convective heat transfer, the cans used for packaging also cannot be made larger than about 2 gallons without increasing the time of the retort process, which then further degrades quality (color, flavor and texture) of the fruit. For these reasons, fruit and syrup are commonly commercially packed in 1 gallon cans. For a typical commercial batch size of 500 gallons of fruit in packing medium, 500 separate cans are needed. Thus a commercial produce processing company that handles millions of pounds of fruits and vegetables per year utilizes a very significant number of these metal cans. A method to eliminate or significantly reduce the number of cans used for packing stock fruits and vegetables will reduce the storage, handling and distribution costs, as well as the environmental footprint of these activities.
In conclusion, there is a long-felt need to improve the sterilization, stabilization, and packaging of harvested fruits, vegetables and other produce that will allow for longer retention of freshness, color, texture and flavor and overall quality, and utilizes less packaging, than is currently possible with conventional retort processes and packaging.